X-ray tube



Dec. 5, 1933.

M. MORRISON X-RAY TUBE Filed Sept. 22, 1925 INVENTOR B 2%2/ ATTORNEY MontFm'dIMmnmson Patented Dec. 5, 1933 NT cries- X-RAY TUBE Montford Morrison, Chicago, 111., assignor, by nicsne assignments, to Westinghouse Lamp Company, a corporation of Pennsylvania Application September 22, 1925 Serial No. 57,836

8 Claims. (01. see-#35) tending toward simplification of design and uni forrnity of operating characteristics and in which the anode and cathode are substantially disposed in separate chambers which provide for the elimination of long discharge paths.

It is an object of the present invention to pro- Vide an X-ray tube in tvhich the cathode and anode are substantially disposed in separate chambers or compartments.

It is a further object of my invention to provide an Xray tube in which long discharge paths are substantially eliminated, thus furnishing a tube which may be operated. in the presence of a substantial gas pressure without liability of detrimehtal'gas ionization occurring.

Further objects of th invention will be rent as the description read and from the accompanying drawing in which the single view illustrates a longitudinal section of an X-ray tube embodying my invention. V

Referring to the drawing the main envelope 2 may be of ethane corresponding to that of the gas-filled lamp type and may consist of any suitable glass, such as a hard glass. The envelope may consist of a bulbous portion 3 having a single neck or arm 4, the latter having a reentrant tube 5 of glass sealed at 6 thereto.

The reentrant tube 5 may be utili ed as support for the anode 7, the latter consisting of a rod of copper or other good heat conducting ma- 40 terial having an insert 8 of thorium or the like or a good ray-emitting substance. The end of the copper rod 7 may be suitably secured by screwsS or the like to a metallic sleevell which is split so as to frictionally engage the-inner surface of the reentrant tube si e may be locked in position by the provision oi a bayonet slot 12 which engages a protuberancelii pressed out of the reentrant tube 5 by heating or the like. A leading-in wire 14 may be secured at one" to the copper rod '7 and at its other end 'may be sealed to a screw base 15 in a manner customarily employed in standard lamp practice. An inter mediate portion 16 of the. leading-in wire may be sealed in the press l? of a supplementary reentrant tube 18, which latter may be fused to an extension 19 of the neck 4. The device may be suitably exhausted by connection to theextension 19 as at 21.

The main or bulbous portion 3 of the'envelope may be divided into separate compartments 22 by means of a glass or other suitable insulating partition 2% which may be fused at 25 to the envelope and to which may also be secured insulating sleeve or housing 26. The housing has an opening 27 at one end of suchsize that the anode may be conveniently slipped therethrough, a smaller opening 28 being provided for exhausting the space within the housing and the compartment 23. The other endof the insulating sleeve 26 is curved at 29 so as to have a radii of curvature corresponding to that of the end 31 of the anode, it being noted that this end of the anode is rounded so as to avoid electrostatic being concentrated, thus eliminating the tendency of overheating at locallized points.

An opening 32 may be provided in the end 2901? the insulating housing 26 and in this opening a thermionic cathode 33 may be and prefi erably is disposed. The cathode 33 may consist of one or more turns of wire such as tantalum, the arrangement with respect to the target 8 being such that electrons from the cathode striking the target will produce X-rays which in turn pass along thelongitudinal of the envelope, through the open space between the turns of the cathode and thence through the end of the envelope to secure a usefulpurpose. The cathode is closely space from the target, the spacing being such that no detrimental ionisation takes place of the residual gas within the envelope. That is to say, mean free path 02 the molecules of residual gas is greater than the space between the anode and cathode so that the liability of electrons striking gas molecules on. their way? to v the anode is reduced to a minimum.

Current for the cathode may be supplied by leads 3e and 35 which in turn are sealed at 36 and-37, respectively, in the glass envelope. Suitable contact caps 38 and 39 secured to the ends of the leads 34 and 35, respectively, may as provided to furnish connections for attaching to a suitable source of supply.

A metallic shield 41 may be secured by screws 42 to the end 29 of theinsulating housing 26, the shield being of such size and material as to effectively screen out undesirable Xn'adiations.

The device may be evacuated through a suitable connection made at the point 21, the gas pressure under which the tube operates being of the order of that of the gas-filled X-ray tubes, say about 1 micron. If desired, a suitable inert gas such as neon, helium, mercury and the like may be employed, the pressure employed. being of the order of that specified.

The present invention is simplified by the separate compartments 22 and 23 in which the anode and the cathode, respectively, are housed. By reason of such construction, long discharge paths extending from the cathode to the lower part of the anode shank 7 are effectively broken by the barrier 24. It is understood, of course, that the space between the insulating housing 26 and the anode shank is so small that ionization therein is efiectively prevented; also that the surface of the inner wall of the insulating housing is so great that no appreciable current leakage takes place thereover.

In addition to the foregoing functions of the insulating housing 26, this member also serves to focus the electron stream emanating from the cathode 33 upon the focal spot 8, whereby a sharp focus may be obtained. This results from the accumulation of electrons upon the curved surface, 43 of the insulatin housing 26 which have a repelling concentrating action upon the electrons coming from the cathode.

Obviously, modifications occur to those skilled in the art, but it is to be appreciated that such modifications as come within the scope of the invention as defined in appended claims are considered by me as falling within the spirit of my invention.

What is claimed is:

1. An X-ray tube comprising an envelope, a partition within said envelope for dividing the space therein into two compartments, an insulating sleeve supported by said partition, a portion of said sleeve extending into one compartment and another portion into the other com-- partment, an anode supported at one end by said envelope and having its other endextending into one end of said sleeve, a cathode mounted in the other end of said sleeve and spaced closely from said anode, and means partially surrounding the end of said sleeve which envelops said cathode for screening out undesirable X-rays.

2. An X-ray tube comprising an envelope, a barrier dividing envelope into an anode and a cathode compartment, an anode supported Within said anode compartment, an insulating sleeve carried by said barrier and surrounding a portion of said anode, said sleeve being closely spaced from said anode, a cathode disposed in said cathode compartment and supported by said sleeve, said cathode being closely spaced from said anode, and an inert gas within said envelope.

3. An X-ray tube comprising an envelope having a bulbous portion and a neck, a reentrant tube within said neck, an anode supported by said tube and having its end projecting into said bulbous portion, an insulating barrier within said bulbous portion for separating the same into two compartments, an insulating sleeve carried by said barrier and surrounding the end of said anode, a cathode mounted in the end of said sleeve and disposed adjacent he end of said anode, said anode and cathode being disposed in axial alignment with the longitudinal axis of said envelope whereby X-rays generated at said anode emerge from said tube along the longitudinal axis thereof.

4. An X-ray tube comprising an envelope having a bulbous portion and a neck, an anode supported by said neck and extending Within said bulbous portion, a partition disposed medially of said bulbous portion, an insulating sleeve supported by said partition and closely disposed adjacent the end of said anode, the end of said sleeve being substantially closed but having an opening therein in axial alignment with the longitudinal axis of said envelope, a helical cathode disposed in said opening, the spacing of the end of said anode and said cathode being such that no appreciable gaseous ionization occurs even in the presence of a substantial gas pre sure, and means for screening out undesirable X-radiations.

5. An X-ray tube comprising an envelope having a bulbous portion and a neck extending there'- from, a reentrant tube within said neck, an anode supported by said tube, the end of said anode extending within said bulbous portion, a partition medially disposed within said bulbous portion, an insulating housing supported by said partition, said housing having its one end substantially closed but having an opening therein for the passage of X-rays, a cathode disposed in the opening, said cathode being formed to pass X-rays without interception, said anode, opening, and cathode being disposed in axial alignment whereby useful X-rays may be generated and emitted from said tube in the direction of its longitudinal axis.

6. An X-ray tube comprising an envelope, a partition for separating said envelope into two compartments, an insulating sleeve carried by said partition, a portion of said sleeve extending on each side of said partition, said sleeve being substantially closed at one end but having an opening of small diameter therein, the other end of said sleeve having a larger opening therein, an anode supported by said envelope and having its end projecting through said larger opening to a point adjacent said smaller opening, said anode being closely spaced from the interior wall of said sleeve and having its end rounded, the interior surface of said sleeve adjacent the end having the smaller opening being concave and a cathode disposed in the smaller opening, said tube containing gas at a substantial pressure.

'7. An X-ray tube comprising an envelope having a spherical bulb and a tubular extension extending therefrom, a reentrant tube secured to said tubular extension at the anode side of said envelope, an anode supportedby said reentrant tube, a partition within said spherical bulb separating the same into two compartments, said partition having a central opening therein through which the end of said anode extends, and a thermionic cathode supported by said partition.

8. An X-ray tube comprising an envelope, 2. reentrant tube secured to the anode side of said envelope, an anode supported at one end of said envelope by said reentrant tube and a cathode supported at the other end of said envelope, a partition intermediate the ends of said envelope and secured thereto, said partition having a tubular portion concentric with the anode surrounding the end thereof, an opening therethrough to permit electrons to pass from said cathode to said anode, said partition supporting said cathode, the spacing of said anode and cathode being such that electrons in passing to said anode do not cause appreciable gas ionization.

MONTFORD MORRISON.

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